c hapter 11. after you have completed this chapter, you should be able to: o bjectives 1....
TRANSCRIPT
CHAPTER 11 CHAPTER 11
AFTER YOU HAVE COMPLETED THIS CHAPTER, YOU SHOULD BE ABLE TO:
OBJECTIVESOBJECTIVES
1. Distinguish between endocrine and exocrine glands and define the terms hormone and prostaglandin.
2. Identify and locate the primary endocrine glands and list the major hormones produced by each gland.
3. Describe the mechanisms of steroid and non-steroid hormone action.
4. Explain how negative and positive feedback mechanisms regulate the secretion of endocrine hormones.
5. Explain the primary mechanisms of endocrine disorders.
6. identify the principal functions of each major endocrine hormone and describe the conditions that may result from hyposecretion or hypersecretion.
7. Define diabetes insipidus, diabetes mellitus, gigantism, goiter, cretinism, and glycosuria.
In this presentation we will discuss the following:
QUICK OUTLINEQUICK OUTLINE
MECHANISMS OFMECHANISMS OFHORMONE ACTIONHORMONE ACTION
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A. Endocrine glands secrete chemicals (hormones) into the blood (Figure 11-1)
B. Hormones perform general functions of communication and control but a slower, longer-lasting type of control than that provided by nerve impulses
C. Cells acted on by hormones are called target organ cells
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MECHANISMS OFMECHANISMS OFHORMONE ACTIONHORMONE ACTION
Page(s) 344-349
D. Nonsteroid hormones (first messengers) bind to receptors on the target cell membrane, triggering second messengers to affect the cell’s activities (Figure 11-2)
MECHANISMS OFMECHANISMS OFHORMONE ACTIONHORMONE ACTION
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E. Steroid hormones bind to receptors within the target cell nucleus and influence cell activity by acting on DNA (Figure 11-3)
REGULATION OF REGULATION OF HORMONE HORMONE
SECRETIONSECRETIONA. Hormone secretion is controlled by homeostatic feedback
B. Negative feedback—mechanisms that reverse the direction of a change in a physiological system (Figure 11-4)
C. Positive feedback—(uncommon) mechanisms that amplify physiological changes
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MECHANISMS OF MECHANISMS OF ENDOCRINE DISEASE ENDOCRINE DISEASE
(Table 11-1)
A. Hypersecretion—secretion of an excess of hormone
B. Hyposecretion—insufficient hormone secretion
C. Target cell insensitivity produces results similar to hyposecretion
D. Endocrinologists have developed many different strategies for treatment (e.g., surgery and hormone therapy)
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PROSTAGLANDINSPROSTAGLANDINSA. Prostaglandins (PGs) are powerful
substances found in a wide variety of body tissues
B. PGs are often produced in a tissue and diffuse only a short distance to act on cells in that tissue
C. Several classes of PGs include prostaglandin A (PGA), prostaglandin E (PGE), and prostaglandin F (PGF)
D. PGs influence many body functions, including respiration, blood pressure, gastrointestinal secretions, and reproduction
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PITUITARY GLANDPITUITARY GLAND (FIGURE 11-6) (FIGURE 11-6)
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PITUITARY GLANDPITUITARY GLAND
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A.Anterior pituitary gland (adenohypophysis)
1. Names of major hormonesa. Thyroid-
stimulating hormone (TSH)
b. Adrenocorticotropic hormone (ACTH)
c. Follicle-stimulating hormone (FSH)
d. Luteinizing hormone (LH)
e. Growth hormone (GH)
f. Prolactin (lactogenic hormone)
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2.Functions of major hormones
a.TSH—stimulates growth of the thyroid gland; also stimulates it to secrete thyroid hormone
b.ACTH—stimulates growth of the adrenal cortex and stimulates it to secrete glucocorticoids (mainly cortisol)
c. FSH—initiates growth of ovarian follicles each month in the ovary and stimulates one or more follicles to develop to the stage of maturity and ovulation; FSH also stimulates estrogen secretion by developing follicles; stimulates sperm production in the male
PITUITARY GLANDPITUITARY GLAND
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2.Functions of major hormonesd. LH—acts with
FSH to stimulate estrogen secretion and follicle growth to maturity; causes ovulation; causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum; causes interstitial cells in the testes to secrete testosterone in the male
PITUITARY GLANDPITUITARY GLAND
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2.Functions of major hormonesd. LH—acts with
FSH to stimulate estrogen secretion and follicle growth to maturity; causes ovulation; causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum; causes interstitial cells in the testes to secrete testosterone in the male
PITUITARY GLANDPITUITARY GLAND
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2.Functions of major hormones
e.GH—stimulates growth by accelerating protein anabolism; also accelerates fat catabolism and slows glucose catabolism; by slowing glucose catabolism, tends to increase blood glucose to higher than normal level (hyperglycemia)1)Hypersecretion during
childhood results in gigantism and during adulthood results in acromegaly
2)Hyposecretion during childhood results in pituitary dwarfism
PITUITARY GLANDPITUITARY GLAND
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2.Functions of major hormones
f. Prolactin or lactogenic hormone—stimulates breast development during pregnancy and secretion of milk after the delivery of the baby
PITUITARY GLANDPITUITARY GLAND
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B. Posterior pituitary gland (neurohypo-physis)
1. Names of hormones
a.Antidiuretic hormone (ADH)
1)Hyposecretion causes diabetes insipidus, characterized by excessive volume of urine
b.Oxytocin
PITUITARY GLANDPITUITARY GLAND
Page(s) 352-354
2.Functions of hormones
a.ADH—accelerates water reabsorption from urine in the kidney tubules into the blood, thereby decreasing urine secretion
b.Oxytocin—stimulates the pregnant uterus to contract; may initiate labor; causes glandular cells of the breast to release milk into ducts
PITUITARY GLANDPITUITARY GLAND
HYPOTHALAMUSHYPOTHALAMUS
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C. The secretion and release of posterior pituitary hormones is controlled by nervous stimulation
D. The hypothalamus controls many body functions related to homeostasis (temperature, appetite, and thirst)
A. Actual production of ADH and oxytocin occurs in the hypothalamus
B. After production in the hypothalamus, hormones pass along axons into the pituitary gland
THYROID GLANDTHYROID GLAND(FIGURE 11-7)(FIGURE 11-7)
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THYROIDTHYROID GLAND GLAND
A. Names of hormones
1.Thyroid hormone—thyroxine (T4) and triiodothyronine (T3)
2.CalcitoninB. Functions of hormones
1.Thyroid hormones—accelerate catabolism (increase the body’s metabolic rate)
2.Calcitonin—decreases the blood calcium concentration by inhibiting breakdown of bone, which would release calcium into the blood
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THYROID GLANDTHYROID GLANDThyroid Hormones are stored in colloid in
thyroid follicles
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THYROIDTHYROID GLAND GLAND
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C. Hyperthyroidism (hypersecretion of thyroid hormones) increases meta-bolic rate
1. Characterized by restlessness and exophthalmos (protruding eyes)
2. Graves’ disease is an inherited form of hyperthyroid-ism
THYROIDTHYROID GLAND GLAND
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D. Hypothyroidism (hyposecretion of thyroid hormones)
1. May result from different conditions
2. Simple goiter—painless enlargement of thyroid caused by dietary deficiency of iodine
THYROIDTHYROID GLAND GLAND
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D. Hypothyroidism (hyposecretion of thyroid hormones)
3. Hyposecretion during early development may result in cretinism (retardation) and during adulthood in myxedema (characterized by edema and sluggishness)
PARATHYROID PARATHYROID GLANDSGLANDS
(FIGURE 11-7)(FIGURE 11-7)
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A. Name of hormone—parathyroid hormone (PTH)
B. Function of hormone—increases blood calcium concentration by increasing the breakdown of bone with the release of calcium into the blood
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ADRENAL GLANDSADRENAL GLANDS(FIGURE 11-13)(FIGURE 11-13)
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ADRENALADRENAL GLANDS GLANDS
b. Mineralocorticoids (MCs)—chiefly aldosterone
c. Sex hormones—small amounts of male hormones (androgens) secreted by adrenal cortex of both sexes
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A. Adrenal cortex
1.Names of hormones (corticoids)a.Glucocorticoids (GCs)—chiefly cortisol
ADRENALADRENAL GLANDS GLANDS
3. Mineralocorticoids—increase blood sodium and decrease body potassium concentrations by accelerating kidney tubule reabsorption of sodium and excretion of potassium
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2. Three cell layers (zones)a. Outer layer—secretes mineralocorticoidsb. Middle layer—secretes glucocorticoidsc. Inner layer—secretes sex hormones
ADRENAL GLANDSADRENAL GLANDS
4. Functions of glucocorticoidsa. Help maintain normal blood glucose
concentration by increasing gluconeogenesis—the formation of “new” glucose from amino acids produced by the breakdown of proteins, mainly those in muscle tissue cells; also the conversion to glucose of fatty acids produced by the breakdown of fats stored in adipose tissue cells
b. Play an essential part in maintaining normal blood pressure—make it possible for epinephrine and norepinephrine to maintain a normal degree of vasoconstriction, a condition necessary for maintaining normal blood pressure
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ADRENAL GLANDSADRENAL GLANDSc. Act with epinephrine and norepinephrine
to produce an antiinflammatory effect, to bring about normal recovery from inflammations of various kinds
d. Produce anti-immunity, anti-allergy effect; bring about a decrease in the number of lymphocytes and plasma cells and therefore a decrease in the amount of antibodies formed
e. Secretion of glucocorticoid quickly increases when the body is thrown into a condition of stress; high blood concentration of glucocorticoids, in turn, brings about many other stress responses (Figure 11-14)
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ADRENALADRENAL GLANDS GLANDS
2. Functions of hormones—help the body resist stress by intensifying and prolonging the effects of sympathetic stimulation; increased epinephrine secretion is the first endocrine response to stress
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B. Adrenal medulla1. Names of hormones—epinephrine (adrenaline) and
norepinephrine
ADRENALADRENAL GLANDS GLANDS
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C. Adrenal abnormalities1. Hypersecretion of glucocorticoids causes Cushing
syndrome: moon face, hump on back, elevated blood sugar levels, frequent infections
ADRENALADRENAL GLANDS GLANDS
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C. Adrenal abnormalities
2. Hypersecretion of adrenal androgens may result from a virilizing tumor and cause masculinization of affected women
3. Hyposecretion of cortical hormones may result in Addison disease: muscle weakness, reduced blood sugar, nausea, loss of appetite, and weight loss
PANCREATIC ISLETSPANCREATIC ISLETS(FIGURE 11-17)(FIGURE 11-17)
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PANCREATIC ISLETSPANCREATIC ISLETS
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1. Glucagon—secreted by alpha cells
2. Insulin—secreted by beta cells
A. Names of hormones
PANCREATIC ISLETSPANCREATIC ISLETS
B. Functions of hormones
1. Glucagon increases the blood glucose level by accelerating liver glycogenolysis (conversion of glycogen to glucose)
2. Insulin decreases the blood glucose by accelerating the movement of glucose out of the blood into cells, which increases glucose metabolism by cells
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PANCREATIC ISLETSPANCREATIC ISLETS
C. Diabetes mellitus (Figure 11-18)
1. Type 1 results from hyposecretion of insulin
2. Type 2 results from target cell insensitivity to insulin
3. Glucose cannot enter cells and thus blood glucose levels rise, producing glycosuria (glucose in the urine)
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FEMALE SEX GLANDSFEMALE SEX GLANDS
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1. Effects of estrogen (feminizing hormone)
a. Development and maturation of breasts and external genitals
b. Development of adult female body contours
c. Initiation of menstrual cycle
A. The ovaries contain two structures that secrete hormones—the ovarian follicles and the corpus luteum; see Chapter 22
MALE SEX GLANDSMALE SEX GLANDS
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1.Effects of testosterone (masculinizing hormone)a.Maturation of
external genitals
c.Beard growthd.Voice changes
at pubertye.Development
of musculature and body contours typical of the male
A. The interstitial cells of testes secrete the male hormone testosterone; see Chapter 22
THYMUSTHYMUS
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A. Name of hormone—thymosin
B. Function of hormone—plays an important role in the development and function of the body’s immune system
PLACENTAPLACENTA
A. Name of hormones—chorionic gonadotropins, estrogens, and progesterone
B. Functions of hormones—maintain the corpus luteum during pregnancy
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PINEAL GLANDPINEAL GLAND
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B. Called third eye because its influence on secretory activity is related to the amount of light entering the eyes
A. A small gland near the roof of the third ventricle of the brain
1. Glandular tissue predominates in children and young adults
2. Becomes fibrous and calcified with age
PINEAL GLANDPINEAL GLAND
C. Secretes melatonin, which:
1. Inhibits ovarian activity2. Regulates the body’s internal clock
D. Abnormal secretion of (or sensitivity to) melatonin may produce seasonal affective disorder (SAD) or winter depression, a form of depression that occurs when exposure to sunlight is low and melatonin levels are high
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OTHER ENDOCRINE OTHER ENDOCRINE STRUCTURESSTRUCTURES
A. Many organs (for example, the stomach, intestines, and kidney) produce endocrine hormones
B. The atrial wall of the heart secretes atrial natriuretic hormone (ANH), which stimulates sodium loss from the kidneys
C. Fat-storing cells secrete leptin, which controls how full or hungry we feel
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CREDITSCREDITS
A.All photos and references are taken from:
Thibodeau, Gary, & Patton, Kevin. (2005). The Human body in health & disease. Mosby.
ISBN: 0-323-03161-7
A.All photos and references are taken from:
Thibodeau, Gary, & Patton, Kevin. (2005). The Human body in health & disease. Mosby.
ISBN: 0-323-03161-7